Abstract: Two technologies are successfully removing volatile organic chemicals (VOCs) from groundwater supplies. Not surprisingly, since the application is new, many of the designs were not optimized for cost. This article presents conclusions from analysis of design and cost data from 53 pioneer installations of packed-column aeration and granular activated carbon (GAC) systems for removing VOCs. A number of VOC treatment methods have been considered by engineers, including conventional water treatment, boiling, reverse osmosis, biological detoxification, aeration, and adsorption. Conventional treatment does not effectively remove VOCs; the other three options work, but need more technical study or are not presently economically feasible. That leaves aeration and adsorption, which are both technically and economically feasible for use in this application. Several dozen full-scale facilities using each process have been construction in the U.S.